These images were captured by a satellite that was launched during the cold war. But, President Bill Clinton allowed releasing spy satellite footage that was "scientifically or environmentally useful.”
Researchers at Columbia University and the University of Utah have used spy images captured between 1975 and 2000 to measure the effect of climate change on Himalyan Range. Himlayan range includes Mount Everest and has tens of thousands of glaciers. But researchers covered only 650 of these glaciers that stretch in a range of 1240 miles or around 2000 kms.